The protocol given to me by my old vet was to give the bitch Panacur for 3 days after whelping. Since I've been doing this I've noticed that when I worm the litter at 2 weeks I don't see any worms whereas before I started doing this I would notice a couple here and there from at least one puppy.
Read the information you recieve here and then ask your vet to be sure. Panacur is fairly strong. You're asking about the bitch only but if I were you, I would still want the vet to give his or her okay. At the very least, let your vet know what you're planning on doing. The vet might have a better plan.
I was told not to use anything stronger than over the counter wormers on my bitch when her pups were around that age. All she had was loose stool. I wormed her pups at the same time and again a week later. That was strictly vet advice.
Are you doing this to worm her after a litter, do you see that she has worms or is her stool just loose?